Air Healthy to Breathe
Under the Clean Air Act, the U.S. Environmental Protection Agency is required to set and review National Ambient Air Quality Standards (NAAQS) for six common outdoor air pollutants (also known as “criteria” air pollutants): nitrogen dioxide (NO2), ground-level ozone (O3), sulfur dioxide (SO2), particulate matter (PM), carbon monoxide (CO), and lead (Pb).
Four of these pollutants (NO2, SO2, CO, and Pb) emit directly from a variety of sources. Ozone is not directly emitted, but is formed when oxides of nitrogen (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight. PM can be emitted, or it can be formed when emissions of NOx, sulfur oxides (SOx), ammonia, organic compounds, and other gases react in the atmosphere.
It is important for states to regulate these pollutants to minimize harmful health effects to Americans. Learn more.

Economic Indicators versus Emissions of Common Pollutants
Since xxxx, California's economy demonstrated continuous growth, its population increased, and its citizens drove more miles.
Concurrently, the combined emissions of common outdoor air pollutants xxxxed by xx%.
Communities directly affect pollutant emissions as populations increase and citizens engage in activities like driving cars. Common outdoor air pollutants are carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM), sulfur dioxide (SO2), and volatile organic compounds (VOCs). This measure encompasses both point and nonpoint source emissions.
Percent Change
Ambient Air Pollution
In 1999, X out of x standards measured in California were at or below the National Ambient Air Quality Standards (NAAQS).
Ambient (or atmospheric) air quality refers to the concentration of pollutants in the outdoor air. Ambient air is regulated by U.S. EPA and maintained by states through the NAAQS, which is the set of guidelines on acceptable concentrations of nitrogen dioxide (NO2), ground-level ozone (O3), sulfur dioxide (SO2), particulate matter (PM), carbon monoxide (CO), and lead (Pb). NAAQS seek to protect the public, especially “sensitive” populations such as asthmatics, children, and the elderly, from harmful ambient air pollutants.
For the purposes of ECOS Results, individual states had discretion with regard to the geographical scope of areas reported.
Percent Above or Below NAAQS Standard
The data reflect measurements taken in Riverside - Rubidoux.